Garden Soil Calculator
Filling a raised bed or topping up a garden takes more soil than most people expect, and ordering by guesswork is costly either way. This calculator computes the volume of soil or compost for a rectangular bed from its length, width, and fill depth, then reports the result in cubic feet, cubic yards for bulk delivery, and the number of bags at your chosen bag size. The bag size is editable to match what you are buying, and the volume is exact, so you can add your own margin for settling.
Garden soil formula
area = length * width (square feet)
volume (cubic feet) = area * (depth inches / 12)
cubic yards = cubic feet / 27
bags = ceil( cubic feet / bag size )
Depth in inches is divided by 12 to convert to feet. One cubic yard is 27 cubic feet. Bags are rounded up because you cannot buy a partial bag.
Garden soil facts
- Many vegetable beds want 8 to 12 inches of good soil for healthy roots.
- One cubic yard equals 27 cubic feet and is the standard bulk delivery unit.
- Bagged soil commonly comes in 1, 1.5, 2, or 3 cubic foot bags.
- Loose soil and compost settle after watering, so ordering a little extra is wise.
- Bulk delivery is usually cheaper per cubic foot than bags for large beds.
Garden soil: frequently asked questions
How do I calculate how much soil I need?
Multiply the bed length by width to get area, then by the fill depth to get volume. Keep length and width in feet and depth in inches, divide depth by 12, and the result is cubic feet. Divide cubic feet by 27 for cubic yards, the unit bulk soil is sold in, or by the bag size for the number of bags.
How deep should garden soil be?
It depends on what you are growing. Many vegetable beds want 8 to 12 inches of good soil, while topping up a lawn or bed may need only 1 to 2 inches. Because the right depth varies by plant and purpose, this calculator takes fill depth as an input so you can match your project.
How many cubic feet are in a cubic yard?
There are 27 cubic feet in one cubic yard (3 feet by 3 feet by 3 feet). Bulk soil, compost, and mulch are usually sold by the cubic yard, so this calculator divides the cubic-feet volume by 27 to tell you how many cubic yards to order for delivery.
What bag size should I use?
Bagged soil and compost commonly come in 1, 1.5, 2, or 3 cubic foot bags. Check the bag label for its volume in cubic feet and enter that here. The calculator divides the total cubic feet needed by your bag size and rounds up, since you cannot buy a partial bag.
Should I add extra for settling?
Loose soil and compost settle and compact after watering and over time, so it is wise to order a little more than the exact calculated volume. A simple approach is to round up your order or add roughly 5 to 10 percent. This calculator gives the precise volume; add your own margin on top.
Official sources
- USDA Natural Resources Conservation Service: Soil basics.
- National Institute of Standards and Technology (NIST): Volume unit conversion (cubic feet and yards).
Reviewed by the CalculatorHub team, edited by James Graham, 16 June 2026. See our methodology.